Electrical transformer coils

ABSTRACT

The invention relates to novel devices for, and methods of, anchoring start, tap or finish leads in a transformer coil, whereby such leads are relieved of stresses during handling and assembly of the transformer coil. The invention comprises a device having a portion adapted to be mechanically anchored to the coil by winding turns of wire thereover, and a connected portion having a lead receiving and protecting portion adapted to extend from a side of the coil.

United States Patent [191 Gaty, m

[ ELECTRICAL TRANSFORMER COILS [76] Inventor: Theodore E. Gaty, III, 1132 ane Allen Road, Lexington, Ky.

[22] Filed: June 5, 1972 [21] Appl. No.: 259,961

[52] US. Cl 336/192, 29/605, 174/138 R [51] Int. Cl. H011 15/10 [58] Field of'Sealch 336/192, 198, 208; 174/135, 138 R [56] References Cited UNITED STATES PATENTS 3,131,372 4/1964 Cahagirone 336/192 3,668,588 6/1972 Walsh, Jr. 336/192 3,518,596 6/1970 Connell 336/192 3,368,176 2/1968 Rechel 336/192 1,164,113 12/1915 Orswell 336/192 X 2,661,446 12/1953 Adcock 336/192 Oct. 16, 1973 3,092,797 6/1963 Wood 336/198 2,779,928 1/1957 Jeffrey 336/192 2,166,841 7/1939 Helgason et al.. 336/192 2,122,894 7/1938 Sager 336/192 3,670,277 6/1972 Deker .I. .T. TETSG/ 192 Primary Examiner-Thomas J. Kozma Attorney-Michael Williams [5 7] ABSTRACT 7 Claims, 15 Drawing Figures PATENTED [IN I 6 I975 SHEET 3 BF 3 1 ELECTRICAL TRANSFORMER COILS BACKGROUND AND SUMMARY The usual transformer coil consists of multiple layers of electric conductor material interspersed with layers of electrical insulation material. The conductor material is usually copper or aluminum and may be of wire or flat sheet form. Usually, wire is wound in specific number of turns and layers and this number is determined by the mechanical size of the wire and the designed width of the layer to produce a transformer coil of engineered capacity.

At the start, finish or tap position in a layer, it is necessary to change the direction of the wire in order to bring the leads out of the coil, usually at one end of the latter which will hereinafter be referred to as the lead exit end. l-Ieretofore, such leads merely extended from the coil end without any anchoring, and provided a convenient handle for a workman to grasp in handling and transporting the coil. Such pulling force applied to the leads caused failures in electrical connection of the leads with the coil and also caused turns adjacent the lead to become unwound, thereby resulting in electrical and mechanical damage to the coil.

My invention provides a low cost anchor for the leads to adequately protect them from the damage above mentioned. The anchor is easily applied to the lead during normal winding of the coil, and therefore requires no drastic change in coil production.

DESCRIPTION OF THE DRAWINGS In the drawing accompanying this specification and forming a part of this application, there are shown, for purposes of illustration, several embodiments which my invention may assume, and in these drawings:

FIG. 1 is a separated perspective view of a presently preferred form of an anchor for a transformer coil lead,

FIG. 2 is a fragmentary, enlarged, fragmentary sectional view of the parts shown in FIG. 1, also in separated relation,

FIG. 3 is afragmentary, top plan view of a part shown in FIG.'2, corresponding to the line 3-3 of FIG. 2,

FIG. 4 is a sectional view corresponding to the line 4-4 of FIG. 3, but with the cover attached,

FIGS. 5 through 9 are fragmentary perspective views showing other embodiments of my invention,

FIG. 10 is a plan view of a transformer coil, showing my invention applied to a start position in a layer of wire turns,

FIG. 11 is an enlarged, fragmentary perspective view of the start position lead shown in FIG. 10,

FIG. 12 is a fragmentary perspective view showing my invention applied to a mechanical tap,

FIG. 13 is a fragmentary plan view showing my invention applied to a loop-out tap,

FIG. 14 is a fragmentary perspective view showing my invention applied to a mechanical tap near that side of the coil which is opposite the lead exit end, and

FIG. 15 is a fragmentary perspective view showing my invention applied to the finish winding of a layer where the finish is near that side of the coil which is opposite the lead exit end.

DESCRIPTION OF PREFERRED EMBODIMENT The device 15 shown in FIGS. 1 through 4 is made of non-contaminating, electrical insulating material, suitable for use in all insulating'mediums embodied in a transformer construction, and has properties capable of satisfactory maintenance of its insulating and mechanical properties when subjected to the operating temperatures of a transformer. Materials presently found suitable are nylon and teflon. The device may be of physical propertions which are dictated by coil requirements. In the presently disclosed embodiment, physical dimensions are given as illustrative of proportions found suitable for many uses.

The device 15 comprises an anchor portion 16 which may be about one-fourth inch wide, 4 inches long and 3/32 inch thick. Top and bottom surfaces of the anchor portion may have transverse serrations 17 to enhance gripping action. Joined to the anchor portion 16, preferably by integral connection, is a lead receiving and protecting portion 18 which may be of the same thickness but preferably wider and somewhat longer. In the disclosed embodiment, the portion is about one-half inch wide and 5 inches long.

At the end connected to the anchor portion 16, the lead receiving and protecting portion 18 is provided with an upstanding head 19, which may be round and is formed with an annular groove 20. At spaced intervals along the portion 18 are pairs of upstanding spaced-apart lugs 21-21.

As seen in FIG. 3, a lead wire L may be brought into the device at right angles to the longitudinal axis thereof, wound around the groove 20 in the head 19 and then disposed lengthwise along the portion 18 and between the spaced lugs 21. Each set of lugs 21 may be spaced apart an amount slightly less than the diameter of the wire at the entrace to the space therebetween so that the wire will be held in the bottom of the space with a snap fit.

In order to electrically insulate the lead wire and to hold it assembled with the portion 18, a cover 22 is provided. The cover 22 may be formed of the same materials the portions 16 and 18 and has an end recessed to receive the head 19. The cover may be held in position overlying the portion 18 in any suitable manner, such as by tape wrapped around the two parts. However, it is preferable to detachably connect the cover and in the disclosed embodiment the recessed portion is provided with a downwardly extending projection 23 which has a snap fit within an opening 24 formed in the head 19. The cover 22 is also formed with pairs of openings 25--25 which receive corresponding projections 21--21 with a snap fit.

Transformer coils are usually wound on a mold or mandrel form which may be round, square or oblong. The cross section of the mold form is determined by the amount of core steel to be inserted in the coil opening which is left after the winding mold or mandrel has been removed. The transformer coil consists of multiple layers of wire windings interspersed with layers of electrical insulation material. There are a number of layers of wire in each transformer coil, the number being determined by the gross number of turns needed for the proper electrical turns ratio divided by the number of turns per layer. The number of turns per layer is determined by the mechanical size of the wire and the designed width of the layer. After suitable electrical insulation, such as cuffed or electrical paper, is would around the mold or mandrel form, the latter is placed in a winding machine which will rotate the form and the wire is thus wound therearound, with adjoining convolutions in contact with each other, as seen in FIGS. 10

and 11. The wire is magnet wire and has an insulating coating of varnish or the like so that the touching convolutions do not short out.

Before the start of the winding operation, the device of my invention is attached to the insulation upon which the layer is to be wound, with the head 19 disposed at the lead exit end of the coil, and the anchor portion 16 lying along the insulation and preferably taped thereto as suggested by the dotted lines in FIG. 10. The starting end of the wire is wound around the groove of the head and snapped between pairs of lugs 21-21, and its extremity projects beyond the end of the portion 18, as seen at 30, for subsequent electrical connection. The cover 22 may then be assembled on the portion 18.

The mandrel form is then rotated so that the wire is wound around the insulation paper and, as this is being done, the wire is also wound over the anchor portion 16 to firmly hold it in place. Once enough wire has been wound over the anchor portion, the tape may be removed. It will be appreciated that when the layer of wire has been wound to the end of the coil opposite the lead exit end, it will have been wound tightly over the entire length of the anchor portion 16 and the latter will be immovably fixed in position. Thus, any pulling force applied to the portion 18 and assembled cover 22 will be absorbed by the anchor portion and the lead wire will be entirely free of stress.

Sometimes a tap must be made in an intermediate portion of a layer of wire. FIG. 12 shows the winding in a direction away from the lead exit end of the coil. In this case, the winding would be made up to the tap portion and then the lead L would be soldered or brazed to the winding, as at 31. My lead securing device would then be disposed in place, with the anchor portion 16 taped to the insulating paper P which separates winding layers, and with the portion 18 overlying the wound part of the layer and extending beyond the lead exit end of the coil. The lead L will then be wound around the groove in the head 19, and snapped between abutments 21-21. The cover 22 will thenbe assembled on the portion 18, and the winding then continued, so as to wind over the anchor portion 16 and thus lock it in place. Since the tapping operation may remove insulation coating from the wire at the tapped joint, it may be preferable to provide additional paper insulation at the point of tappage.

Instead of a mechanical tap, as above described, the coil specifications may call for a loop-out tap, as shown in FIG. 13. In this case, the coil wire is wound around opposite sides of the groove in the head 19 and then snapped between the abutments 21-21. In all other respects, the disposition of the lead anchoring device would be the same as described in connection with FIG. 12.

In some cases, the tap must be made near that end of the coil which is opposite the lead exit end and insufficient wire windings are available to firmly grasp the anchor portion 16. In such cases, and as illustrated in FIG. 14, the preceding winding layer at such coil end is wound over the end of the anchor portion 16, as seen in dotted lines at 35. Then the anchor portion is bent around the end of the insulating paper P and doubled over on to the outer surface of this paper, and the winding layer is wound over the doubled part. Thus, the immediate layer and preceding layer of wire windings serve. to lock the anchor portion 16 in place. The tap may then be made, with the tap lead wound around the groove in the head 19 and snapped between the abutments 212l. Thereafter, the cover 22 is snapped in place, and the winding is continued over the cover.

If the finish winding terminates at that coil end which is opposite the lead exit end, the anchor portion 16 may again be grasped by the preceding winding layer, as seen in FIG. 15, and doubled over so that the lead end may be wound around the groove of the head 19 and snapped between the abutments 21-21. The addition of the cover 22 completes the assembly.

DESCRIPTION OF OTHER EMBODIMENTS In commercial transformer production, it is standard practice to avoid connection of the coil magnet wire to a terminal of the transformer, and normally a lead of standard conductor wire is electrically connected to the end of the magnet wire.

With reference to FIG. 5, an anchoring device 15a is shown which is somewhat similar to the device heretofore described, except that the portion 18a is modified to provide a longitudinal groove 40 for receiving the magnet wire lead 300. An electrical socket 41 of any standard construction has a crimp connection 42 with the lead end of the magnet wire and is closely received within an opening 43 at the end of the portion 18a and is thus locked in place against longitudinal movement. A cover, similar to the cover 22, may be connected to the portion 18a to prevent lateral movement of the socket 41.

The socket 41 has the usual electrical spring contacts to receive an electrical plug 44, and the latter has a crimp connection 45 with a conductor lead. It will therefore be appreciated that the plug 44 need merely be inserted into the socket 41 to make an electrical connection suitable for attachment to the terminal of a transformer.

A further embodiment is shown in FIG. 6, wherein the anchor portion 16b and head 19b are similar to parts heretofore described. In this embodiment, the portion 18b is trough-shaped in cross-section to receive the magnet lead wire. The ends of the trough may be folded over the lead wire and either taped or heatsealed together.

In the embodiment shown in FIG. 7, the anchor portion 16c and head 19c are similar to previously described parts. In this case, the portion 18c is formed as a tube and has an opening 50 through which the lead wire is inserted for disposition within the tube. In the embodiments shown in FIGS. 6 and 7, the cover plate 22 would be eliminated.

The embodiments shown in FIGS. 8 and 9 are similar to those heretofore described except that the cover 22d in each case is formed as an integral part of the device. In FIG. 8, the cover 22d has an integral connection 51 with the head 19d. In FIG. 9, the cover 22d has an integral connection 52 with the end of portion 18d, an opening 53 being provided to pass the magnet lead wire.

I claim:

1. An electrical coil assembly, including at least one wire layer wound about an insulating support, and a lead for said wire layer adapted to be connected to a source of electrical energy, the improvement comprismg,

a strap-like anchor member for relieving said coil lead of handling stresses, said anchor member being a molded product of electrical insulating material and having one end portion extending crosswise of said wire layer and firmly secured thereto, the opposite end portion of said anchor member having means for receiving and protecting said lead and being freely disposed to provide a convenient hand-hold by which said coil assembly may be handled and thereby relieve said lead of handling stresses, and a head is formed intermediate said end portions, and said lead is connected to said head.

2. The construction according to claim 1 wherein said one end portion is disposed on said insulating support and said wire layer is wound thereover to clamp said one end portion between it and said insulating support.

3. The construction according to claim 1 wherein said head extends from one side surface of said straplike anchor member and has a peripheral groove into which said lead is at least partially wound.

4. The construction according to claim 3 wherein at least one side surface of said one end portion is provided with crosswise serrations to grip said wire layer.

5. The construction according to claim 1 wherein said coil assembly has opposite ends, one end constituting a lead exit end, said wire layer being wound on said insulating support from said lead exit end in a direction toward the other end of said coil, with its lead extending free from said lead exit end,

said one end portion of said anchor member being disposed on said insulating support prior to winding of said wire layer and the latter being wound thereover to anchor the same,

said other end portion of said anchor member being disposed free at said lead exit end.

6. The construction according to claim 3 wherein said one side surface at said opposite end portion is provided with longitudinally spaced pairs of abutments extending therefrom, said lead being disposed between the pairs of abutments with a snap fit,

and a cover overlying said opposite end portion and having longitudinally extending pairs of openings corresponding to said abutments and receiving the same with a snap fit.

7. The construction according to claim 1 wherein said coil assembly has opposite ends, one end constituting a lead exit end, and a plurality of superposed wire layers with insulating sheets between them, said layers and sheets extending to the other end of said coil assembly,

said anchor member being formed of flexible insulating material,

said one end portion having a distal end part clamped between an inner wire layer and the insulating sheet underlying the same, the flexibility of said anchor member permitting said one end portion to be bent around said underlying insulating sheet at said other end of said coil assembly so that said opposite end portion may extend toward said lead exit end of said coil assembly. 

1. An electrical coil assembly, including at least one wire layer wound about an insulating support, and a lead for said wire layer adapted to be connected to a source of electrical energy, the improvement comprising, a strap-like anchor member for relieving said coil lead of handling stresses, said anchor member being a molded product of electrical insulating material and having one end portion extending crosswise of said wire layer and firmly secured thereto, the opposite end portion of said anchor member having means for receiving and protecting said lead and being freely disposed to provide a convenient hand-hold by which said coil assembly may be handled and thereby relieve said lead of handling stresses, and a head is formed intermediate said end portions, and said lead is connected to said head.
 2. The construction according to claim 1 wherein said one end portion is disposed on said insulating support and said wire layer is wound thereover to clamp said one end portion between it and said insulating support.
 3. The construction according to claim 1 wherein said head extends from one side surface of said strap-like anchor member and has a peripheral groove into which said lead is at least partially wound.
 4. The construction according to claim 3 wherein at least one side surface of said one end portion is provided with crosswise serrations to grip said wire layer.
 5. The construction according to claim 1 wherein said coil assembly has opposite ends, one end constituting a lead exit end, said wire layer being wound on said insulating support from said lead exit end in a direction towarD the other end of said coil, with its lead extending free from said lead exit end, said one end portion of said anchor member being disposed on said insulating support prior to winding of said wire layer and the latter being wound thereover to anchor the same, said other end portion of said anchor member being disposed free at said lead exit end.
 6. The construction according to claim 3 wherein said one side surface at said opposite end portion is provided with longitudinally spaced pairs of abutments extending therefrom, said lead being disposed between the pairs of abutments with a snap fit, and a cover overlying said opposite end portion and having longitudinally extending pairs of openings corresponding to said abutments and receiving the same with a snap fit.
 7. The construction according to claim 1 wherein said coil assembly has opposite ends, one end constituting a lead exit end, and a plurality of superposed wire layers with insulating sheets between them, said layers and sheets extending to the other end of said coil assembly, said anchor member being formed of flexible insulating material, said one end portion having a distal end part clamped between an inner wire layer and the insulating sheet underlying the same, the flexibility of said anchor member permitting said one end portion to be bent around said underlying insulating sheet at said other end of said coil assembly so that said opposite end portion may extend toward said lead exit end of said coil assembly. 